Overhead projectors of the type shown in U.S. Pat. No. 3,979,160 and U.S. Pat. No. Des. 244,602 are widely used in making various types of visual presentations concerned with business matters, economics and a wide variety of educational disciplines. The presenter stands near one side of the overhead projector and places a series of transparencies on the top transparent stage of the light box forming the base of the projector. Images carried by the transparencies are reflected by the elevated projection head through its lenses and mirror onto a suitable remote projection screen.
It is customary for a presenter to interrupt the visual presentation periodically, to make comments and answer questions and the like. Such periods of interruption are usually accompanied by turning off the projector, followed by turning it back on following the interruption. This is somewhat inconvenient for the presenter as well as for the audience. The audience becomes accustomed to a humming sound from the projector and the frequent turning off and on of the projector during a presentation can in itself be annoying, tending to interfere with concentration.
To deal with the above simple problem, which heretofore has not been solved in a convenient and economical way, a simple projected light blocking flip panel attachment according to the invention is provided on the elevated projection head which can be conveniently operated between two positions of use by the presenter when it is desired to briefly interrupt a presentation for any of the mentioned reasons.
In one position, the panel hangs freely by gravity in front of the lens of the projection head to block or interrupt the light being projected onto a remote screen. In the second position of use, the panel is flipped up on its flexible hinge to assume an elevated non-light blocking position on the projection head, either horizontal or inclined. The panel attachment is easily operated by a flick of the finger, is lightweight and durable. It can be formed of opaque plastics and attached to the projection head without defacing or in any way structurally altering the same.
For example, a flexible hinge strip can be provided on the flip panel having conventional minute hook and loop pile components, one of which can be adhesively secured to a surface of the projection head.
The cost of the attachment is minimal, rendering the device ideally suited as a "give away" to customers of manufacturers of the projectors. If desired, the flip panel may be included as an improvement feature on new projectors. Extreme simplicity and convenience of use are inherent in the invention.
The use of the invention allows the presenter to run the projector continuously, without turning it off and on during interruptions in the presentation. The device does not interfere in the slightest with normal usage of the overhead projector, and if its use is not desired, the device can simply remain in the inactive flipped-up position.
Other objects and advantages of the invention will become apparent to those skilled in the art during the course of the following description.